Grouting as a repair/strengthening solution for earth constructions

Earth, as a building material, has been used since ancient times, and is still being used with that purpose. It was used for building shelters, houses, temples and even military constructions, like fortresses. As a consequence, currently, there is a great architectural heritage stock on this kind of constructions. Nevertheless, earthen materials are very sensitive when compared with modern materials, since they are more vulnerable to external aggressive agents, revealing most of the times a faster degradation rate. From a structural perspective they present a very low tensile strength, a low compressive strength and a fragile behaviour, making the earthen structures strongly vulnerable to earthquakes. The structural damage in this kind of structures manifests, in general, in the form of cracks or voids. Repairing these cracks is fundamental in order to obtain an improved structural behaviour, especially if the earth construction was built in a seismic zone. Injecting mud grouts may constitute a feasible and reliable solution for repair this kind of damage. Although, mud grouts experience many problems that hinder their application and the knowledge about them is still very limited. This requires that deep studies have to be carried out in order to solve their problems and to make this solution reliable. In this paper it is discussed the methodology that should be established for the design of mud grouts suitable for earth constructions. But first a summarized explanation about earth constructions and their problems is presented. This results from an ongoing PhD research that still is in an initial phase, and it aims, precisely, the development of grouts specifically to be applied in earth constructions.Fundação para a Ciência e a Tecnologia (FCT